Carbonyl groups can be found in monosaccharides. As a result, they’re categorised as either aldose or ketose.
Aldose refers to monosaccharides that contain an aldehyde group. Ketose refers to monosaccharides that contain a ketone group. Fructose, also known as ketohexose, has the chemical formula C6H12O6 and contains six carbon atoms and a keto group.